アルミニウムの押出しH形材の非対称曲げにおける変形

抄録

Plastic deformation of an extruded aluminum H-beam was investigated under an unsymmetrical bending condition. The deformation of the cross-section under unsymmetrical bending was characterized through comparison with the deformation under symmetrical bending and pure twisting conditions. An H-beam specimen was set with the web axis inclining by ψ degree from the bending plane (the horizontal plane). Then, bending moment was applied on the H-beam specimen using a cantilever type bending apparatus modified to fit for unsymmetrical bending. Both the transverse bending moment and twisting moment caused by the in-plane unsymmetrical bending were measured. The deformation of the cross-section was also determined. When the web plane coincided with the bending plane (symmetrical bending) the web of an H-beam was not deformed. However, the flange showed sagging deformation. When the web plane was perpendicular to the bending plane, the web was deformed into a shape of a character "C". The flangs was only rotated around the junction between the web and flange. Under unsymmetrical bending, the web was deformed into a shape of a character "S", while the flange deformation was a combination of the sagging and rotation. When the inclination angle ψ was small the sagging deformation of the flange was predominant. On the contrary, the rotation of the flange was predominant when the inclination angle ψ became close to 90°. These results are utilized for preventing the deformation of the cross-section under unsymmetrical bending.